The ProblemObstructive sleep apnea (OSA) is a sleep-related breathing disorder that involves a decrease or complete halt in airflow despite an ongoing effort to breathe. It is a common yet serious disorder characterized by repeated pauses in breathing during the sleep cycle. Approximately 18 million Americans are afflicted with OSA, though an estimated 90 percent of patients remain undiagnosed or untreated. Studies have identified a causal relationship between OSA and a number of cardiovascular and metabolic diseases including hypertension, diabetes, stroke, congestive heart failure and sudden cardiac death. Patient compliance can be an issue in treating OSA and can limit the effectiveness of currently available treatments which include lifestyle changes, continuous positive airway pressure (CPAP) devices and surgery. Currently, there are no approved pharmacologic treatments for OSA. StatusA phase 2 study (OB-204) evaluating the safety and efficacy of Qnexa for the treatment of obstructive sleep apnea (OSA)was a single-center, randomized, double-blind, placebo-controlled parallel group trial. It included 45 obese men and women (BMI 30 to 40 kg/m2 inclusive), 30 to 65 years of age with OSA (AHI greater than or equal to 15 at baseline), who had not been treated with, or who were not compliant with continuous positive airway pressure (CPAP) within three months of screening. Patients were randomized to placebo or full-dose Qnexa (15 mg phentermine / 92 mg topiramate CR). Patients underwent a four-week dose titration followed by 24 weeks of additional treatment. All patients were also provided with an intensive lifestyle modification program focusing on diet and exercise. Overnight polysomnography was performed at baseline, Week 8 and Week 28. The primary endpoint was the change in AHI between baseline and Week 28; secondary endpoints included weight loss, oxygen saturation and changes in blood pressure. Highlights of the study include:
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